Research on the Complex Coupling Mechanism and Numerical Simulation of Multi-Physics in a Top-Cathode Rare-Earth Electrolytic Cell
摘要
This paper establishes a mathematical model for the multi-physics coupling in a top-cathode rare-earth electrolytic cell, focusing on the complex interactions between multiphase substances and multiple physical fields. Using the finite element method, a numerical simulation was conducted to thoroughly investigate the interplay among the electric field, electrochemistry, multiphase flow, temperature field, and concentration field. The results indicate that in the electric field, the cathode current density is approximately 7.38 × 104 A/m2, the anode current density is about 7.00 × 103 A/m2, and the molten salt voltage drop is approximately 5.9 V. In terms of the flow field, a distinct vortex forms in the molten salt region between the cathode and anode, with a maximum molten salt flow rate of 0.21 m/s in this area. Regarding multiphase flow, the gas volume fraction at the molten salt surface can reach up to 9.57 pct, while it is very low in the bottom region of the electrolytic cell. In the thermal field, Joule heating of the molten salt is the primary heat source, accounting for approximately 82.1 pct of the total input power, with the electrochemical heat source contributing about 4.5 pct. For the concentration field, when the active substances participating in the electrochemical reaction are in excess, the consumption rate of active ionic reactants approaches a linear relationship, regardless of whether a constant current or constant voltage input is applied to the electrodes. This consumption rate is inversely proportional to the charge carried by the ions.